In Third Generation Partnership Project (3GPP) long term evolution (LTE) Release 8 (R8) uplink (UL), wireless transmit/receive units (WTRUs) may transmit their data (and sometimes their control information) on the physical uplink shared channel (PUSCH). The evolved Node B (eNB) may schedule and control PUSCH transmission from each WTRU using an UL scheduling grant, which may be carried on a physical downlink control channel (PDCCH) format 0. As part of the uplink scheduling grant, the WTRU may receive control information on the modulation and coding set (MCS), the transmit power control (TPC) command, uplink resource allocation (e.g., the indices of allocated resource blocks), and the like. The WTRU may then transmit its PUSCH on the allocated UL resources using the corresponding MCS at a transmit power set by the TPC command.
The UL may also need to signal certain control signaling such as, but not limited to, acknowledgement/negative acknowledgement (ACK/NACK), Channel Quality Indicator (CQI), scheduling request (SR), and sounding reference signal (SRS) to support transmission of downlink (DL) and UL transport channels. If the WTRU has not been assigned an UL resource for data transmission, e.g., PUSCH, then the control information may be transmitted in an UL resource specially assigned for UL control signals on the PUCCH. These resources may be located at the edges of the total available cell bandwidth (BW). The transmit power for PUCCH may be controlled to ensure that the PUCCH is received at the cell site at an appropriate power.
In LTE R8, PUSCH and PUCCH transmissions of a given WTRU are scheduled to occur at different times. LTE-Advanced (LTE-A) may support simultaneous transmissions of PUSCH and PUCCH. Additionally, the LTE-A UL may support multiple transmit antennas (e.g., up to 4 antennas) with a possible maximum of two code words (transport blocks) for data transmission per UL component carrier. Multiple transmit antennas may be used for PUCCH and SRS transmissions, respectively. An antenna gain imbalance (AGI) may occur when using multiple antenna transmissions in the UL.